Large earthwakes are more likely to occur during the two lunar phases when tidal stresses on Earth are the highest, Japanese study reveals.
A new study by Japanese researchers has shown earthwakes are more likely to occur at times of full or new moon, when tidal stresses on Earth are the highest.
The scientists from the University of Tokyo analyzed three different seismic global databases plus Californian and Japanese records and watched for large earthwakes (magnitude 5.5 or greater) that happened in the last 2 decades.
They focused on the fornight and reconstructed the size and amplitude of the tidal stresses and found that the largest earthwakes happened indeed on days near new or full moons.
At these two points during the lunar cycle, the Earth, the sun and the moon align causing the gravitational tug of the moon on the planet to be more intense. This is something scientists had long speculated, and this study suggests that is likely.
For example, the Sumatra and Indonesia earthwake in 2004 (magnitude: 9.3), the one in Maule, Chile in 2010 (magnitude 8.8) and Tohoki-oki in Japan 2011 (magnitude 9.0) coincided with high tidal stress. More so, 9 of the 12 largest earthwakes in the last 20 years happened around a new or full moon.
Surprisingly, the research didn’t found any correlation between small earthwakes and tidal stresses. Nonetheless a study led by Nicholas Van der Elst from the US Geological Survey, found a link between small tremors in the San Andreas Fault and the moon’s position. They happened when the moon was in its waxing phase, building up to the new moon.
We took a look into Latin America’s latest earthwakes to see if they coincided with full or new moon phases. On September 13th a 6.0 magnitude earthwake shook Colombia, three days before the full moon. But in Peru the 10th September’s 6.0 earthwake doesn’t coincide neither with a full nor new moon phase.
Van der Elst told the Los Angeles Times the primary causes for an earthwake happen within the Earth’s crust, with tectonic plates moving and causing a snap. He says the moon and its tidal stresses add a little 1% or less of top of the tectonic loading.
His position might be asserted. So far all studies have established correlations between
LatinAmerican Post | Maria Andrea Marquez